OA13227A - Modular metal bridge and its production method. - Google Patents

Abstract

The invention relates to a modular metal bridge, comprising a platform (B), supported by two longitudinal girders made from longitudinal elements (1a, 1b...), connected by transverse members (2) and upper joint elements (23). According to the invention, the upper joint elements are supported by the transverse members (2), connecting the elements (1a, 1b) of the two girders (1, 1') by means of spacer bodies (20) with a height adjusted such as to give a continuous deck (B) at the level of the upper faces (12) of the upper flanges of the longitudinal girders (1, 1'). Said deck can be covered by a concrete slab (5), fixed to the girders and, in a particularly advantageous manner, the girders (1, 1') are articulated and have a longitudinal upwardly-convex profile such as to bring the concrete slab (5) into compression by a slight downward flex of the two girders (1, 1').

Description

The invention relates to a modular metal bridge and its method of production. The invention allows the construction of temporary bridges but can also be applied to the rapid and economical realization of medium-span bridges.

During military operations, it is often necessary to construct river or valley crossing structures or to quickly rebuild destroyed bridges. For this purpose, the armies can have collapsible bridges as described, for example, in the document US-A-4,825,492 but it is also known for a long time modular bridges type "BAILEY" consisting of a number of beams and metal profiles making it possible to achieve with few means and a reduced team, two longitudinal support members forming lattice girders and connected at their base by transverse elements carrying a decking.

The BAILEY bridge has been the subject, since its creation, many improvements but retaining the same general layout.

For example, the document US-A-4,965,903 describes a bridge of this type also comprising two lateral lattice girders connected to their bases by spacers on which a decking rested. In this technique, the lower part of each lateral beam consists of tubular sections of rectangular section placed end to end, the adjacent ends of two consecutive sections being connected by several splints secured to the end of each beam by metal plates passing between the splints. As a result, the connection between two consecutive profiles is not very visible since the fishplates and plates are placed inside the profiles but the whole remains unattractive because, as in a BAILEY bridge, the bridge is supported by two Lateral lattice girders also forming railings.

Moreover, even in this recent technique, a very large number of elements are used, the assembly of which remains rather long and complex.

To solve these problems, the applicant company has proposed, in French Patent No. 2,801,328, a new method for producing a modular bridge comprising, for each span between two supports, two longitudinal beams consisting of elements placed end to end and connected by transverse spacers, the assembly supporting a platform.

Such an embodiment has the advantage of requiring only a small number of structural elements, longitudinal beam elements, transverse struts and upper joining elements, respectively, which, in the French patent embodiment 2 801 328 can be simple metal brackets for the installation of wooden sleepers or slab formwork panels, or prefabricated slabs provided with sealing means with the upper flanges of the two beams.

In addition, the beam elements consist of trapezoidal or rectangular section boxes, which facilitates the installation and, for equal weight, gives the beams excellent rigidity. On the other hand, the number of elements of construction is particularly reduced because it is possible to make in advance beam elements of great length, for example ten meters. Indeed, specialized military units are now equipped with lifting means to set up and assemble elements of several tons.

But another advantage of this arrangement lies in its external appearance, much more aesthetic than the usual military bridges worn by two longitudinal truss beams. A modular bridge of the type described in the French patent 2 801 328 has, on the contrary, an external appearance very similar to that of conventional bridges and, therefore, such a technique can be used not only for temporary bridges, for example to military use, but also for the rapid and economical construction of medium-span metal bridges which fit particularly well into the environment.

The applicant company has, however, continued its studies in order to further improve the technique described in its previous patent and has managed to further simplify the realization of such a metal bridge. On the other hand, it has been possible to develop different techniques of construction and implementation of the bridge, particularly in the case where the platform is made of concrete. The invention therefore generally relates to a modular metal bridge comprising a substantially horizontal platform supported on two longitudinal beams and consisting of at least three series of elements prepared in advance, respectively a series of elements. longitudinal members each comprising two substantially horizontal spacers, respectively lower and upper, connected by at least one substantially vertical core, said beam members being joined end to end to form at least two parallel longitudinal beams spaced from each other, a series of longitudinally spaced transverse spacers, each having two ends provided with removable fastening means on mating portions of the beam members and a series of connecting members between the upper flanges of the beam members.

According to the invention, the upper connecting elements rest on the transverse connecting struts between the elements of the two beams by means of wedging members height adjusted to provide a continuous floor at the upper faces of the soles upper longitudinal beams.

In a first preferred embodiment, the upper connecting elements consist of a series of rectangular plates resting on the transverse spacers by means of longitudinal profiles whose height is adjusted so that the upper faces of said plates extend. at the upper faces of the upper flanges of the two longitudinal beams to form a continuous platform.

In this case, the upper flanges of the beam members form two raceways for vehicles passing over the deck, said upper flanges being treated to promote adhesion. The junction plates between the upper flanges of the beams can then consist of simple light gratings.

But the platform consisting of the upper flanges of beams and junction plates between them can also be used as lost formwork for the casting of a concrete dalie.

In another embodiment, the connecting elements between the two longitudinal beams consist of concrete slabs resting on the one hand on the upper flanges of the longitudinal beams and, on the other hand, on the transverse struts via setting means of determined height, to define a continuous platform.

Preferably, according to the arrangement described in the previous patent 2,823,128, each longitudinal beam element forms a hollow box with a quadrangular cross-section with two substantially horizontal faces forming the upper and lower flanges of the beam and two side faces provided with means for fixing the spacers or, possibly, bodyguard supports.

In a particularly advantageous embodiment, the consecutive elements forming a longitudinal beam are connected in pairs, by their adjacent ends, at their lower flanges by a connecting means articulated about a transverse axis and bear one of them. on the other, at their upper flanges, by a transverse wedging means whose width is adjusted to give the longitudinal beam, between two spaced apart supports, a convex profile upwardly long and having an arrow sufficient to compensate for the bending down of each beam under the effect of the own weight of the bridge and applied loads.

Preferably, the connection means articulated between two consecutive beam elements comprises, at the end of each element, at least one longitudinal piece of connection with a corresponding piece of the adjacent element, each connecting piece being fixed on the soleplate. lower part of the element and having at least one portion projecting beyond the end thereof and in which is formed a transverse axis orifice and that, to the assembly of two consecutive beam elements , the projecting portions of the connecting pieces overlap so that the orifices are aligned and centered on the same transverse axis to allow the threading of a securing rod.

Furthermore, the wedging means between the upper flanges of two consecutive beam elements comprises, at the end of each element, a shim formed of a metal plate having two parallel transverse edges, respectively an inner edge welded along an end of the upper flange and an outer edge bearing, on assembling two consecutive beam elements, against an outer edge of the corresponding shim of the adjacent element, each shim having a width adjusted so that, after assembly of two consecutive beam elements, their upper flanges are placed in planes forming between them an angle I determined so that the entire longitudinal beam follows the desired length profile.

Advantageously, after assembling the consecutive beam elements and placing it in place of wedging means, the adjacent ends of said beam elements are connected, at least temporarily, to their upper parts, by means of blocking the articulation, so that the set of elements behaves as a continuous beam for the transport and the establishment of it.

Particularly advantageously, the entire platform of the bridge is covered with a concrete slab secured at least with the upper flanges of the two beams and they have a convex profile upwardly convex with an arrow set for the compressing the concrete by bending down said beams under the effect of the weight of the bridge and applied loads.

Preferably, each longitudinal beam consists of at least two consecutive elements connected, on the one hand to their lower parts, by a hinge about a transverse axis and on the other hand, to their upper parts, by at least one variable length connecting member for maintaining the convex longitudinal profile of the beam between two spaced supports, at least during the realization of the concrete slab, the length of said upper connecting members being reduced, after making the slab to allow bending down the beam with compression of the slab to a support position on top of each other of the upper ends of the adjacent ends of the two consecutive elements.

Each upper connecting member between two consecutive beam elements may consist of at least one hydraulic cylinder having a body and a piston rod respectively articulated on each of the consecutive elements, or a sandbox limiting a chamber filled with sand with a drain hole allowing a partial evacuation of the sand for the compression of the slab by reducing the deflection of the longitudinal beam.

In the case where the deck of the bridge rests on at least three spaced supports, respectively two end abutments and at least one central stack, each longitudinal beam comprises, at each central stack, a central element resting on the stack and having two ends connected to the ends opposite the adjacent beam elements, by transverse axis joints placed substantially at the level of the upper flanges, the other elements of the beam being interconnected by joints placed substantially at their lower flanges . The invention also covers a method for producing a metal bridge in which at least two longitudinal beams are constructed each consisting of at least two beam elements placed end to end, is set up on two apart supports a bridge span composed of two beams interconnected by spacers, at least two longitudinal sections are placed on said spacers and a series of junction plates extending between the upper faces of the longitudinal beams and forming with the longitudinal beams is placed on said profiles. this is the platform of the bridge.

The longitudinal beams prepared in advance by butt jointing consecutive elements may be thrown longitudinally from one of the supports or prepared on the bank and raised to be placed on the supports. it is also possible to prepare spans with two beams connected by spacers and put them on the supports, either by launching or by lifting.

Each longitudinal beam consisting of at least two consecutive elements whose adjacent ends are connected to their bases by a transverse joint, in the case where the beam is thrown by longitudinal thrust from one of the supports, the first element of Beam placed the most forward lowers, during launch, by rotating around its articulation and can come to rest on a floating support that accompanies the front end of said first element to the second support, the latter being equipped with lifting means which raises the first member to bring it into alignment with the next member and place it on the second support. Other advantageous features, within the scope of protection of the invention, will become apparent in the following description of certain particular embodiments, described by way of non-limiting examples and shown in the accompanying drawings.

Figure 1 is a cross sectional view of a bay member according to the invention.

Figure 2 is a partial view in perspective of the end of a span member.

Figure 3 shows, on an enlarged scale, the assembly of the ends of two longitudinal beam members.

Figure 4 is a top view of the end of a beam, the upper sole being removed.

Figure 5 shows another connecting means articulated between two consecutive beam elements.

Figure 6 is a schematic view, in elevation, of a beam consisting of three consecutive elements.

Figure 7 shows schematically, in longitudinal section, a span of bridge curved upward and covered with a slab.

Figure 8 shows a sand box connection between two consecutive elements.

Figure 9 shows, in top view, the realization of a bias bridge.

Figure 10 shows schematically an articulated deck bridge resting on a central stack.

In FIG. 1, a cross-section span element is shown, the left half-view being a current section and the right half-section view of the end of the span, according to line I, I of FIG. Figure 3.

As in the embodiment of the previous patent FR 2 801 328, each bay element 1 comprises, in a general manner, two elements of longitudinal beams 1,1 'spaced symmetrically on either side of a longitudinal median plane P of the span and connected between eüx rigidly by transverse spacers 2. These may be formed of tubes, as in the case of the previous patent, which provides.une excellent rigidity for a reduced weight. However, it is also possible to use more simply, section I sections whose dimensions and number are determined to ensure the necessary rigidity. These sections 2 are simply bolted at their ends 21 to fastening plates 14 distributed along the lateral faces of the two beams 1, Γ and forming gussets with holes in advance for fixing the end 21 a profile 2 also pierced in advance.

Each beam 1,1 'can, moreover, be provided with two sets of gussets 14i, 14e formed on its two lateral faces to allow the attachment of railing C or, as will be seen later, the realization of an extra bay.

In a particularly advantageous manner, as in the previous patent 2,823,128, each longitudinal beam has the shape of a box with a rectangular section comprising a lower sole 11 and an upper sole 12 connected by two vertical webs 13, respectively internal 13i and external 13th .

In the particularly simple embodiment shown in FIGS. 1 and 2, usable, for example, for a temporary bridge for military use, the deck platform consists only of the upper flanges 12 of the two beams 1, 1 'between which are inserted junction plates 23 resting simply on the spacers 2 through longitudinal profiles 20 which thus constitute setting members whose height can be adjusted. so that the upper faces of the joining plates 23 are at the same level as the flanges 12, 12 'and form, with them, a continuous floor B.

The distance between the axes of the beams 1,1 'can be determined so that the upper flanges 12 of the two beams 1, form two tracks for the circulation of the vehicles directly on said flanges, the latter being treated by example striated, to ensure proper adhesion. In this case, the plates 23 inserted between the flanges 12 and resting on the spacers 2 by regularly distributed profiles 20 may consist of simple gratings.

Such an embodiment allows a particularly simple and rapid construction of a bridge to one or more traffic lanes from several series of prefabricated elements, respectively box beam elements, spacers, longitudinal profiles and plates. junction.

For example, for crossing a river, the beam members 1 may be assembled on the bank to form a beam of desired length which may be either raised in block or longitudinally pushed the quadrangular box section of the beam. to avoid the risk of spills.

The two beams being placed one next to the other, at the desired distance, on two spaced apart supports D, the spacers 2 are bolted to the gussets 14, the longitudinal sections 20 are placed on the spacers and then set up the consecutive panels 23 to form the deck B-platform.

If we have the necessary lifting equipment, we can also realize the span on the bank by setting up in advance the spacers 2, and possibly the longitudinal sections 20 before launching the entire span for the lay on the two separated supports. From a span thus made, it is easy, in case of need to widen the bridge to achieve a second lane. Indeed, a third longitudinal beam can be made by butt assembly of prefabricated elements and this beam is then pushed onto the existing span and then removed from it to be placed at the desired distance by lifting means mounted on the span. Since the new beam is also provided with fastening gussets 14, it is possible, from the existing span, to place and bolt the spacers 2 and then the longitudinal sections 20 and finally to put the joining plates 23.

The same technique can be used for the realization of a definitive bridge, with a concrete platform. This may consist of prefabricated slabs which rest directly on the upper flanges 12 of the two beams 1, Γ and on the spacers 2, via the profiles 20.

But it is also possible to make the junction between the upper flanges 12 by means of simple thin plates placed on the profiles 20 and lying in the extension of the upper faces of the flanges 12 of the two beams, the assembly thus forming a formwork lost on which can be poured a continuous slab. In this case, the flanges 12 are advantageously provided with connectors welded to the flanges and sealed in the concrete to ensure the joining of the slab with the two longitudinal beams.

According to another characteristic of the invention, applicable particularly in the case where the platform is made of concrete, it is particularly advantageous to connect the consecutive elements of a beam by means of articulations, as shown diagrammatically in FIGS. 3 to 6.

In this case, indeed, as shown in Figures 3 and 4, two consecutive beam members 1a, 1b are interconnected at their lower part by an articulated connection means 3 and bear one on the other, at their upper part, by means of wedging 4.

The articulated connection means 3 comprises at least two connecting pieces 31, 32 fixed respectively on the ends of the two beams 1a, 1b at their lower semesiles 11 and provided with orifices 33 which, after assembly of the beams 1a, 1b, are aligned to allow the threading of a securing rod 34. For this purpose, as shown in Figure 3, the ends 11 12 ', 13', respectively of the lower sole 11, the upper sole 12 and each core 13, are set back from the plane Q of junction between two consecutive elements 1a, 1b, so that each connecting piece 31, 32 fixed to the end of an element ta, 1b has a portion 3Γ, 32 which protrudes beyond the junction plane Q and in which is formed an orifice 33 centered on an axis 30. At the assembly of the elements 1a, 1b, the two projecting parts overlap and the orifices 33 come to focus on one and the same axis 30 placed in the plane of junction Q, a rod 34 then being threaded into the orifices so aligned.

The two consecutive beam elements 1a, 1b are thus articulated, at their lower part, about the axis 30 and tend to bear against one another at their upper part, under the effect of their own weight. elements and loads applied. This support is effected by means of a wedging means consisting, at the end of each beam, of a plate 41 forming a transverse wedge having an inner edge 42 welded to the end 12 'of the upper sole. 12 and an outer edge 43 placed substantially in the junction plane Q.

As shown in FIGS. 3 and 4, these two connecting pieces form clevises, respectively female 31 and male 32 which fit into one another.

The female clevis 31 consists of two plates, one of which is shown in perspective in FIG. 5, which are welded on either side of each core 13 of the beam element 1a as well as on the lower flange 11. At the opposite end of the adjacent element 1b is fixed the male clevis 32 consists of a plate provided with a central slot which fits on the lower part of the core 13 of the element 1b and is welded on the latter and on the lower soleplate 11. The ends 31 'of the two parts of the female clevis 31 are thinned so as to provide a space in which the end 32' of the male part 32 engages, these parts protruding 3Γ, 32 'being provided with orifices 33 in which is threaded the securing rod 34.

Of course, it is possible, to better distribute the forces, to have several articulated connecting pieces 3 over the width of the longitudinal beams 1.

It is also possible, in the embodiment shown in FIG. 5, to equip the adjacent ends of the two beams 1a, 1b with a certain number of plates 35a, 35b spaced apart from each other so as to form screeds in which they come. inserting ribs 36, the plates and the fishplates being provided with holes which are aligned along two axes allowing the passage of two connecting rods 34 '.

As indicated above, the two consecutive beam elements 1a, 1b thus articulated at their lower part are supported on one another, at their upper part, by means of a wedging means 4 constituted by end of each beam member 1a, 1b, a flat 41 extending transversely to the longitudinal axis of the beam, over the entire width of the upper flange 12 and welded to the end 12 'thereof along an inner edge 42. In addition, the two wedges 41 welded respectively to the flanges 12 of the two beam members 1a, 1b are supported on one another by an outer edge 43 which, after assembly of the two beam elements, is placed in the junction plane Q passing through the axis of articulation 30.

Preferably, as shown in FIG. 3, the two wedges 41 have a wedge-shaped profile whose thickness increases between the internal edge 42 of thickness equal to that of the upper sole 12 and the outer edge 43 of which The thickness is intended to accommodate the horizontal stresses resulting from the support of the two elements one on the other under the effect of the load.

Each shim 41 extends cantilevered from the upper flange 12 and is welded to the upper parts of the ends of the two webs 13 of the beam which are provided with a notch having a profile conjugate to that of the wedge 41 .

In addition, at its two ends, the wedge 41 is supported by two vertical gussets 15 extending in a console from a transverse bracket 16 fixed on the outer face of the vertical core 13.

As shown in FIG. 1, the brackets 16 fastened respectively to the two webs 13 of the beam can serve, inwardly, to bolt a spacer 2 and, outwardly, to attach a guard. C. On the other hand, the brackets 16a, 16b fixed at the opposite ends of the two adjacent beam members 1a, 1b are provided with orifices 16 'for the passage of a prestressed bar 17 which is tensioned and whose ends are threaded for the engagement of a nut not shown.

In this way, for the construction, for example, of a bridge crossing a river, the span elements A each comprising two beam elements 1, 1 'can be assembled on the shore by fitting one into the other. other their connecting pieces 31, 32, each beam member being provided at one end of a female piece 31 and at its other end with a male piece 32.

The assembling of the articulations can be carried out flat and, after assembly, the bars 16 are passed through the orifices 16 which are tensioned so as to apply the external edges 43 of the opposite spacers 41 to one another.

Thus, the consecutive span elements can be assembled together on the shore, and after slinging, are lifted by a lifting means such as a crane to be placed on two spaced piles D, as shown schematically on the figure 6.

However, when the span is launched by longitudinal thrust from the shore, it may be interesting not to block the joints and let, on the contrary, they open.

When launching, in fact, the most forward element tends to tilt down when its center of gravity exceeds the support on the abutment. Its front end then descends and can come to rest on a pontoon. It is, therefore, no longer necessary to place a counterweight at the back to balance the cantilever.

The launch can then continue by advancing the pontoon with the element that it supports up to the opposite bank on which a hoist can lift the front end of the bay to rest on the second abutment.

According to another particularly advantageous feature of the invention, the width of the wedges 41 can be adjusted so as to give the span thus formed a defined longitudinal profile having, for example, as shown in FIG. 6, a convexity turned towards the high to provide, between the upper level of the bay and the level of the supports D, an arrow f to compensate for the bending of the beam under the effect of its own weight and loads applied in service. Indeed, because the successive bay elements are hinged to one another at their lower part, the width I of the two wedges 41 can be adjusted so as to leave, after support, a certain opening determining an angle (i) between the planes of the upper flanges 12, 12b of two consecutive elements 1a, 1b. It is thus possible to bring on the site beam elements and spacers prepared in advance, in order to achieve bay elements which are then fixed one after the other to form a span. This can then be lifted or pushed to rest on abutments or spaced piles.

For relatively large spans requiring a number of consecutive span elements, it is possible to prestress the entire length of the span by means of cables 18 passing through guides fixed to the webs 13 of the beam members, and supported at their ends on the first and the last element A of the bay, the positions of the guides being determined so as to give the pre-stressed cables a profile calculated according to the forces to be supported.

As indicated above, the circulation platform can be constituted, simply, by the upper faces of the flanges 12, 12 'and the plates 23 inserted therebetween.

However, the use of articulated beam elements for the realization of a span having a slightly convex profile upward is particularly interesting in the case where the platform of the bridge consists of a concrete slab extending over all the length of the span, as shown schematically in Figure 7.

As indicated above, this slab 5 may be cast on the continuous floor (B) constituted by the flanges 12 of the beams 1 and the thin plates inserted therebetween, the assembly forming a lost formwork. But it can also realize the slab in the form of prefabricated concrete elements placed one after the other and between which are 'formed concrete joints to form a continuous slab ..

As in the case of Figure 6, the longitudinal beams 1 consist of a series of consecutive elements 1a, 1b, 1c ... whose adjacent ends are connected at their lower parts by joints 3 and are kept apart from each other to their upper parts so that their upper flanges 12a, 12b are placed in planes forming between them a determined angle so that the whole of the longitudinal beam takes a profile in long convex towards the above.

As before, wedging means 4 are interposed between the upper flanges 12a, 12b. However, in the case where the bridge is covered with a concrete slab, the longitudinal beams 1 are associated with a means of maintaining their profile in convex length at least during the casting and hardening of the concrete slab, the wedges 41a, 40b being slightly spaced from each other, as shown in Figure 8.

In the case of FIG. 7, this means of maintaining the profile of the beams 1 comprises a set of tie rods 6 bearing on the concave lower face of the beam by push rods 61 forming a punch at each articulation 3, the beam 1 being thus subtended.

After pouring the slab 5 and hardening the concrete, the tension of the tie rods 6 may be slightly reduced so that, under the effect of the self weight of the span, the deflection of the latter decreases, the concrete 5 coming into compression until the support is placed on one another wedges 4 placed at the upper part of the beams.

As indicated above, the upper flanges of the beams 1, 1 'are provided with projecting parts forming connectors, which are sealed in the concrete slab 5 so that the slab is secured to the beams and contributes to the strength of the slab. 'together.

In the embodiment of FIG. 8, two consecutive elements 1a, 1b of the beam are connected, at their lower parts, by a hinge 3 of the type described above and, at their upper parts by a connecting member of variable length. 60 which, in the example shown, consists of two sandboxes each comprising a cylindrical body 62 and a piston 63 hinged respectively on the vertical webs of the two elements 1a, 1b and limiting an inner chamber 64 filled with sand and provided with an orifice 65 closed by a removable cap.

As shown in Figure 8, during the casting of the slab 5, the sandboxes 60 are adjusted so that the ends of the wedges 41a, 41b are slightly spaced apart from each other. After pouring and hardening of the concrete, the orifices 65 are open and the sand 64 can escape allowing the upper parts of the two elements 1a, 1b to be brought together until their wedges 41a, 41b bear against each other. one on the other, this approximation determining the setting in compression of the concrete 5 under a determined effort.

However, other arrangements are possible, for example the replacement of sandboxes by simple hydraulic cylinders.

Of course, the invention is not limited to the details of the embodiments which have just been described as a simple example, but also covers all variants using equivalent means. Thus, in Figures 6 and 7, there is shown an articulated span resting on two spaced apart abutments D and wherein the beam elements 1a, 1b ... are articulated to their lower parts. In the case, however, of a bridge resting on an intermediate stack D ', it would be advantageous to place thereon an intermediate element 10' connected to the adjacent elements 1e, 1f of the two bays by articulations 3 'placed at upper flanges of the beams, to allow to give the two span a profile convex convex up.

Furthermore, because the beam elements 1a, Ta are provided on their lateral faces with gussets 14i, 14e regularly spaced apart, it is possible to offset longitudinally one of the beams 1 relative to the parallel beam T a distance equal to the spacing between two fasteners 14. In this case, it is still possible to install the spacers 2 and fix them on the lateral faces of the two beams 1, T but the offset allows, advantageously, to make a bridge at an angle, the direction of the span forming a non-right angle with the direction of the support D.

The modular bridge that has just been described therefore has multiple advantages and, in particular, given the hoisting equipment that can be available for the realization and implementation of a span, it is possible to use elements in box of a significant length, for example ten meters. Such elements can, in fact, be made in> factory and brought by the road to the construction site, this one can be supplied with containers of 12 meters making it possible to have, in a desired number, all the necessary elements, to namely, box girder elements provided in advance with their gussets and their joints, transverse crosspieces, longitudinal profiles and junction plates and various accessories such as, for example, railing elements or sidewalks that can be attached to the side faces of the outer beams by short struts. In this respect, it should be noted that in addition to its aesthetic appearance, the modular bridge according to the invention has the advantage of not limiting the clearance gauge between the two carrier beams, as in the case of bridges of the type BAILEY, the deck being placed on the upper face of the supporting beams.

The realization of a span by means of prefabricated elements articulated one after the other thus has many advantages. However, in some simple cases, the beam members could simply be fixed one after the other to make continuous beams of variable length.

Moreover, the use of box girders of rectangular or trapezoidal section is particularly advantageous, but it would also be possible to use beam elements having another section, for example a single-core I-section.

Claims (32)

1. Modular metal bridge comprising a substantially horizontal platform (B) supported on two longitudinal beams (1, Γ) said bridge being made by assembling at the site of at least three sets of elements prepared in advance, respectively, a series of longitudinal elements (1a, 1b ...) each comprising two substantially horizontal, respectively lower (11) and upper (12) spaced apart flanges, connected by at least one substantially vertical core (13), said beam elements ( 1a, 1b ...) being assembled end to end to form at least two parallel longitudinal beams spaced apart from each other, a series of longitudinally spaced transverse struts (2), "each having two ends provided with releasable attachment to mating portions of the beam members, and a plurality of junction members (23) between the upper flanges of the beam members, characterized by r the fact that the upper connecting elements (23) rest on the transverse struts (2) connecting the elements (1a, 1b) of the two beams (1, T) via wedging members (20) having a height adjusted to provide a continuous floor (B) at the upper faces (12) of the upper flanges of the longitudinal beams (1,1 '). 2. Metal bridge according to claim 1, characterized in that the upper connecting elements consist of a series of rectangular plates (23) resting on the transverse struts (2) via longitudinal profiles (20) of which the height is adjusted so that the upper faces of said plates (23) extend at the upper faces of the upper flanges (12) of the longitudinal beams to form a continuous floor (B). 3. Metal bridge according to one of claims 1 and 2, characterized in that the upper flanges (12,12 ') of the beam elements (1, T) form two raceways for vehicles passing over the bridge. 4. Metal bridge according to claim 3, characterized in that the upper flanges (12, 12 ') of the beam elements (1, T) are treated to promote the adhesion of vehicles traveling on the bridge. 5. Metal bridge according to one of the preceding claims, characterized in that the connecting plates (23) between the upper flanges (12,12 ') of the beams (1,1') consist of grating. 6. Metal bridge according to one of the preceding claims, characterized in that each transverse spacer consists of a metal section (2) having two ends (21) each fixed by bolting on a fastening gusset (14) arranged on a lateral face 13 of a longitudinal beam member (1,1 '). 7. Metal bridge according to claim 1, characterized in that the connecting elements consist of concrete slabs resting, on the one hand, on the upper flanges (12,12 ') of the longitudinal beams (1,1'). and, on the other hand, on the transverse struts (2) by means of wedging means (20) having a height determined to define a continuous platform. 8. Metal bridge according to one of the preceding claims, characterized in that each longitudinal beam member (1, 1 ') forms a hollow box with a quadrangular cross section having two substantially horizontal faces forming the flanges, respectively upper (12). and lower (11) of the beam and two side faces (13i, 13e). 9. Metal bridge according to one of the preceding claims, characterized in that the upper flanges (12, 12 ') of the two beams (1, Γ) and the plates (23) extending between them form a formwork lost for the casting of a concrete slab (5) covering the assembly. 10. Metal bridge comprising a platform resting on at least two longitudinal beams (1, 1 ') each consisting of a series of elements prepared in advance (1a, 1b ...) and connected end to end by their ends adjacent, and wherein two consecutive elements (1a, 1b) of a longitudinal beam (1) are interconnected at their lower flanges (11e, 11b) by a connecting means (3) articulated around a transverse axis and bear against one another, at their upper flanges (12a, 12b), by a transverse wedging means (4), characterized in that the width of each wedging means (4) ) is adjusted to give the longitudinal beam (1), between two spaced apart supports (D), an upward convex profile upwards and having an arrow (f) sufficient to compensate for the downward bending of each beam (1) under the effect of the own weight of the bridge and the loads applied. Metal bridge according to claim 10, characterized in that the articulated connection means (3) between two consecutive beam elements (1a, 1b) comprises at the end of each element (1a) at least one piece. longitudinal (31) connecting with a corresponding piece (32) of the adjacent element (1b), each connecting piece (31, 32) being fixed on the lower flange (11) of the element (1) and having at at least one portion (3Γ, 32 ') projecting beyond the end (11') thereof and having an orifice (33) therebetween. transverse axis and that, when two consecutive beam elements (1a, 1b) are assembled, the projections (31 ', 32') of the connecting pieces (31, 32) overlap so that the orifices ( 33) are aligned and centered on the same transverse axis (30) to allow the threading of a securing rod (34). 12. Metal bridge according to one of claims 10 and 11, characterized in that the wedging means (4) between the upper flanges (12) of two consecutive beam elements (1a, 1b) comprises, at the end of each element, a formed shim, of a metal plate having two parallel transverse edges, respectively an inner edge (42) welded along one end (12 ') of the upper sole (12) and an outer edge (43). ) coming, in support, to the assembly of two consecutive beam elements (1a, 1b), opposite an outer edge (43b) of the corresponding shim (41b) of the adjacent element (1b), each shim (41) having a width adjusted so that, after assembling two consecutive beam members (1a, 1b), their upper flanges (12a, 12b) are placed in planes forming an angle I between them so that the whole beam longitudinal follow the profile in long desired. 13. Metal bridge according to one of claims 10 to 12, characterized in that, after the assembly of two consecutive beam elements (la, 1 b) and the establishment of the wedging means (4), the adjacent ends of the two beam members (1a, 1b) are connected, at least temporarily, to their upper part, by a connecting means (17) ensuring the sequestration of the two consecutive elements so that the set of elements behaves as a continuous beam for the transport and the establishment of this one. 14. Metal bridge according to claim 13, characterized in that the upper connecting means between two consecutive beam elements (1a, 1b) is at least one longitudinal bar (17) provided with clamping means for the compression of the wedging means (4). 15. Metal bridge according to one of claims 9 to 14, characterized in that the entire platform (B) of the bridge is covered with a concrete slab (5) cast on the upper flanges (12) of the two beams (1, Γ) and the joining plates (23) and that the longitudinal beams (1, Γ) have an upwardly convex upward profile having an arrow (f) set for compressing the concrete (5). ) by bending down said beams (1, 1 ') under the effect of the own weight of the bridge and applied loads. 16. Metal bridge according to claim 15, characterized in that each longitudinal beam (1) consists of at least two consecutive elements (1a, 1b ...) whose adjacent ends are connected to each other, at least to their lower part by a hinge (3) for giving to the beam (1), between two supports (D) apart, a convex profile upwardly convex, said beam (1) being associated with a holding means (6) of said profile in convex length, at least during the casting of the concrete slab (5) on the platform (B) of the bridge. 17. Metal bridge according to claim 16, characterized in that each articulated longitudinal beam (1) is subtended by a set of tie rods (6) bearing on its concave lower face by push rods (61) punching at the level of each articulation (3) - 18. Metal bridge according to claim 16, characterized in that each longitudinal beam (1) consists of at least two consecutive elements (1a, 1b ....) connected on the one hand, at their lower part, by a hinge (3) about a transverse axis and at the other hand at their upper part, by at least one connecting member (60) of variable length for maintaining the convex long profile of the beam (1) between two spaced apart supports (D), at least until hardening of the concrete slab (5). 19. Metal bridge according to claim 18, characterized in that the length of the upper connecting member (60) between two consecutive beam elements (1a, 1b) is adjusted to give each longitudinal beam (1), between two spaced apart supports (D), a convex profile upwardly convex and that, after casting on the platform of a concrete slab (5) and hardening thereof, the consecutive elements (1a, 1b) are supported, at their upper part, by a wedging means (4) fixing the profile of the longitudinal beams (1,1 ') whose bending downwards, under the effect of the self-weight and the loads applied, determines a compression setting of the concrete slab (5). 20. Metal bridge according to one of claims 18 and 19, characterized in that the upper connecting member (60) between two consecutive beam elements (1a, 1b) consists of at least one hydraulic cylinder having a body and a piston rod articulated respectively on each of the consecutive elements (1a, 1b). 21. Metal bridge according to one of claims 18 and 19, characterized in that the upper connecting member between two consecutive beam elements (1a, 1b) consists of at least one sandbox (60) comprising a body (62) and a piston (63) bearing respectively on each of the beam members (1a, 1b) and limiting a chamber (64) filled with sand with a drain hole (65) allowing partial evacuation of the sand after pouring and hardening of the concrete slab (5) for compressing it by decreasing the deflection of the longitudinal beam (1). 22. Metal bridge according to one of claims 10 to 21, comprising an apron resting on at least three spaced supports, respectively two end abutments (D) and at least one central stack (D '), the deck comprising a platform resting on at least two longitudinal beams (1, 1 ') consisting of prefabricated elements placed end to end having two spaced apart in height, respectively lower (11) and upper (12), characterized in that at each central stack (D '), each longitudinal beam comprises a central element resting on the stack and having two ends connected to the adjacent ends of the beam elements (1e, If) which surround it, by articulations (3') with transverse axis placed substantially at the level of the upper flanges (12), the other elements of each beam (1) being interconnected by joints placed substantially at their lower flanges es (11). Metal bridge according to one of the preceding claims, characterized in that each longitudinal beam element is provided, along at least one lateral face (13), with a plurality of gussets (14) regularly spaced apart for fixing at least one transverse spacer (2). Metal bridge according to Claim 23, characterized in that the elements (1a, Ta) of two parallel beams (1, 1 ') are offset longitudinally by a distance corresponding to the spacing between two successive gussets (14). fixing a spacer (2) so as to make a span at an angle to its supports (D). 25. Process for producing a metal bridge, characterized in that a series of longitudinal beam elements (1a, 1b ...), a series of spacers (2), are produced in advance. a series of longitudinal profiles (20) and a series of upper joining panels (23), said series being brought to a construction site of the bridge comprising at least two spaced apart supports (D), at least two longitudinal beams each consisting of of at least two beams elements (1a, 1b) placed end to end, is placed on the two supports (D) a bridge span consisting of two longitudinal beams (1, T), interconnected by the spacers (2), at least two longitudinal sections (20) are placed on said spacers (2) and a series of consecutive panels (23) extending between the upper faces of the longitudinal beams (FIG. 1, 1 ') and forming with them the platform me (B) of the bridge. 26. The method of claim 25, characterized in that, after having formed two longitudinal beams (1,1 ') each consisting of at least two consecutive elements (1a, 1b), it is laid on two spaced supports (D) the two beams (1,1 ') parallel to each other and spaced apart from each other, are placed spacers (2) which are fixed at their ends (21) on the side faces (13) of the two beams (1, T), the longitudinal profiles (20) are placed on the spacers (2), and the plates (23) are placed on the profiles (20). 27. Method according to one of claims 25,26, characterized in that the longitudinal beams (1, Γ) are prepared in advance by butt assembly of beam elements (1a, 1b ...). and are thrown by longitudinal thrust from one of the supports (D). 28. The method of claim 27, characterized in that each longitudinal beam (1) consisting of at least two consecutive beam elements (1a, 1b) whose adjacent ends are connected at their base by a transverse joint (3). ), the first foremost beam element is lowered during the thrust launch from a first support, rotating around its articulation and is placed on a support that accompanies the front end of said first element until the second support, the latter being equipped with a lifting means which raises the first element to put it in alignment with the next element and the laying on said second support. 29. Method according to one of claims 25 to 28, characterized in that, after providing a bridge span consisting of two longitudinal beams (1, Γ) connected by spacers (2) and connecting plates (23). on at least one side of the span, at least a third longitudinal beam parallel and spaced apart from one of the beams of the span by a distance corresponding to the length of the spacers (2), a series of spacers (2) fixed at their ends (21) on said spaced beams, longitudinal profiles (20) are placed on the spacers (2) and then a series of junction plates (23) on the profiles (20), the width platform (B) is doubled. 30. The method of claim 29, characterized in that the third longitudinal beam is pushed longitudinally on the span already built and then placed at the desired distance by lifting means mounted thereon. 31. A method of producing a metal bridge span comprising two spaced longitudinal beams (1, Γ) each having an upper flange (12) and a series of junction elements (23) disposed between the upper flanges (12, 12). ') of the two beams (1, Γ), at the level thereof, so as to form a platform (B), characterized in that the two longitudinal beams are given a convex longitudinal profile upwards and that the platform is covered with a concrete slab (5) in at least a portion, which is compressed by the downward bending of the two beams (1, Γ) under the effect of the weight of the bridge and the applied loads. 32. The method of claim 31, characterized in that the longitudinal beams (1, 1 ') consist of elements (1a, 1b ...) placed end to end whose adjacent ends are connected to their lower part by transverse joints (3) making it possible to give each longitudinal beam (1) a profile convexly upwards, that each beam (1) is associated with means (6, 60) for maintaining a determined spacing between the parts upper adjacent ends of the beam members (1a, 1b) for maintaining the convex long profile during the realization of the concrete slab (5) and that, after curing the concrete, allowing said upper parts of the elements to be brought together ( 1a, 1b) for compressing the slab (5) by reducing the deflection (f) of the articulated longitudinal beams.